A system of image formation which exhibits photographic characteristics of ultra high contrast (especially with gamma values of at least 10) is required in the graphic arts field for achieving good reproduction of continuous tone images by means of dot images, and for achieving the good reproduction of line images.
The methods in which hydrazine derivatives are used disclosed, for example, in U.S. Pat. Nos. 4,224,401, 4,168,977, 4,166,742, 4,311,781, 4,272,606, 4,221,857 and 4,269,929 are known methods in which high contrast photographic characteristics are obtained using stable development baths. With these methods, photographic characteristics of high speed with ultra high contrast are obtained and, since it is possible to add high concentrations of sulfite to the development baths, the stability of the development baths with respect to aerial oxidation is much better than that of a lith developer.
Furthermore, low speed light-room photosensitive materials which contain hydrazine derivatives as widely used in the reverse process in photographic plate making operations have been disclosed, for example, in JP-A-60-14038, JP-A-60-162246, JP-A-61-238049, JP-63-8846 and Japanese Patent Application Nos. 62-65116 and 62-218648. (The term "JP-A" as used herein signifies an "unexamined published Japanese patent application".)
On the other hand, the photographic plate making process has become more complicated as a result of the diversification of printing materials, and demands have arisen for rationalization of operation and improved energy conservation. Moreover, when photographing screened images and line drawings, or when making contact reverse exposures using ultra-high contrast sensitive materials, electrostatic charges accumulate as a result of contact friction arising from contact between the photosensitive materials themselves or contact with the surface of some other material, or peeling apart, and this causes dust to become attached to the photosensitive material or to the original film and traces of this dust remain as pin-holes after development processing. This is a problem in that these pin-holes must be repaired or the exposure must be made again. Techniques for improving the charging characteristics of the photosensitive materials, using surfactants for example, have been introduced to ameliorate such problems, but these techniques cannot be said to be adequate. Thus, the charging properties are lost when the material is developed and processed and there is virtually no improvement in respect of the aforementioned pin-holes when the film is subsequently used as an original.
Furthermore, changes in dimensions of the photographic material due to expansion or shrinkage of the hydrophilic colloid layers is a very serious disadvantage in the plate making processes when the reproduction of dot images and precise line drawings is required for multi-color printing.
Various devices have been used conventionally to improve the dimensional stability of silver halide photographic materials.
For example, a technique in which the ratio of the thicknesses of the hydrophilic colloid layer and the support is specified has been disclosed in the U.S. Pat. No. 3,201,250, and methods in which a polymer latex is added to the hydrophilic colloid photographic layers have been disclosed in JP-B-39-4272, JP-B 39 17702, JP-B-43-13482, JP-B-45-5331 and U.S. Pat. Nos. 237,600, 2,763,625, 2,772,166, 2,852,386, 2,853,457, 3,397,988, 3,411,911 and 3,411,912. (The term "JP-B" as used herein signifies an "examined Japanese patent publication".)
It is possible to improve the dimensional stability of silver halide photographic materials due to variations in temperature and humidity using these techniques.
However, it is not possible to prevent changes in dimensions which originate from the development processing of silver halide photographic materials using these techniques. The changes in dimensions which accompany development processing occur with silver halide photographic materials as a result of the development processing, the dimensions after development being different from those at the time of exposure, and this is a very serious problem when silver halide photographic materials are used.
A technique in which vinylidene chloride underlayers are used has been disclosed in Japanese Patent Application No. 62-94133 for improving the dimensional stability in respect of development processing.
However, it is not possible to ameliorate the problem of dimensional stability with respect to development processing completely using this technique.
These problems are of special importance in the case of silver halide photographic materials which exhibit ultra-high contrast in respect of rationalization of the plate making process industry, energy conservation and the improvement of printed material quality, and it is very desirable that silver halide photographic materials which are not liable to pin-hole formation and with which the change in dimensions is slight should be developed for this purpose.